
A lot depends on the experience of handlers, dog and bitch. Four novices (ideally you have a handler for the bitch too) spells potential problems!
I have the mating in the garden, and introduce bitch to dog with the bitch offlead and dog on. This way the bitch is less likely to turn on the dog as she is free to get away. When her willingness has been assessed I let the dog loose too for final flirtation, then put the bitch on the lead. A maiden dog and bitch can get it terribly wrong if left to their own devices, and one, or both, can be quite seriously hurt, so supervision and assistance is vital. Assuming all goes well, when the dog is ready to dismount he is assisted (keeping tails out of the way) and the pair restrained from moving till the tie breaks naturally (between about 10 minutes to an hour or more).